Adjustable ladder



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ADJUSTABLE LADDER Filed March 13, 1945 v 14' V7 A lNvENToR ALEXANDER L. PRUTSMAN BY FIG. 5 j

ATTORNEY Patented Aug. 6, 1946 l 2,405,269 ADJUSTABLE LADDER Alexander L. Prutsman, Portland, Oreg.

Application March 13, 1945, Serial No. 582,502

1 Claim.

This invention relates in general to ladders having adjustable extensions at the bottoms of the sidesJ or legs to enable one side or leg or stile to be extended below the other so that the ladder can be brought into desired upright position even though standing on sloping ground.

An object of the present invention is to provide a simple attachment for an ordinary ladder by means of which either leg can be caused to extend below the other, so as to enable the bottom of the ladder to be adjusted for the sloping or uneven surface of the ground on which the ladder is obliged to stand.

Several attachments for ladders, which are designed to accomplish the same general object, have been invented. These, however, do not appear to have been introduced into public use to any considerable extent. The reasons for their lack of widespread use I believe to be due to the fact that such attachments are more or less expensive and are quite troublesome to install and use. As a result, persons using ladders prefer to follow the old, but less satisfactory and more dangerous, method of placing blocks under one leg cr the other to compensate for the unevenness of the ground. Some of the devices which have been invented for this purpose ernn ploy an adjustable attachment which is required to be changed from one leg of the ladder to the other, depending upon which leg is required to be made longer, thus necessitating a certain amount of time and inconvenience in making the desired adjustment. Other devices which have been invented for the saine purpose seek to reduce this amount of time and inconvenience by having adjustable attachments on the ends of both legs of the ladder. However, this in turn means an increased cost for each ladder.

A particular object of the present invention is to provide an adjustable ladder in which the adjusting attachment is required to be placed on one leg only and need not be removed from that leg regardless of the direction in which the ground slopes.

A further object of this invention is to provide a simple, inexpensive attachment which can be easily and quickly installed on any ordinary ladder and which attachment, when combined With the ladder, will result in producing the desired adjustable ladder.

I attain the above mentioned objects and incidental advantages by using an ordinary ladder and rst making one leg of the ladder shorter than the other and then installing an adjustable leg extension on the shorter leg, and further, by

making and arranging the cooperating parts in the manner hereinafter briefly described with reference to the accompanying drawing.

In the drawing: Y

Fig. l is a drawing, in isometric perspective, o an adjustable ladder embodying my invention;

Fig. 2 is a front elevation, partly in section, of the lower portion of the ladder of Fig. l, drawn to a larger scale, and showing the ladder adjusted for uneven ground;

Fig. 3 is an elevation of the adjustable attach-v ment alone, showing the inside face. this View being assumed to be taken along the line 3-3 of Fig. 2;

Fig. 4 is a fragmentary elevation of the outside face of the ladder leg adjacent to the adjustable attachment, the view being taken as indicated by the arrows lin Fig. 2; and

Fig. 5 is a fragmentary iront elevation drawn to a reduced scale, of the same ladder, but showing the bottom of the ladder adjusted so as to rest on ground sloping in an opposite direction from that indicated in Fig. 2.

In all the figures the same parts are indicated by the same'reference characters.

In carrying out my invention I use an ordinary ladder comprising the usual runas 22 and legs or Stiles IG and I I, and first cut off a portion of the bottom end of one of the legs below the bottom rung. Thus, in the ladder of Figs. 1, 2 and 5 a portion has been cut oif from the bottom of the leg l0, causing this leg to be considerably shorter than the other leg II of the ladder. It does not matter which of the two ladder legs is shortened in this manner.

Near the bottom of the shortened leg I0 a small metal plate I2 is attached on the outer face, as shown in Figs. 2 and 4. This small plate I2 is preferably attached to the outer face of the ladder leg by a pair of screws I3, the heads of which are counter-sunk in suitable recesses in the plate I2. The outer face of the plate I2 is serrated or formed with teeth, as indicated in Fig. 2. In the shortened leg I0 of the ladder a pair of holes are bored and a pair of clamping bolts |14 and I5 are inserted through these holes, the holes and bolts lbeing in alignment and being arranged along the center line of the leg. With these changes the ladder is now ready for the adjustable attachment.

The adjustable attachment I6 is formed preferably from a piece of material of the same ap.-V

proximate cross-section as the ladder legs. The adjustable attachment I6 has longitudinal slots I'I and I8, both of the same length, which are in alignment along the longitudinal center line of the piece. As apparent from the drawing, the clamping bolts I4 and I5 extend through these slots and the slots are of suflicient length to enable the adjustable attachment I6 to be arranged on the ladder leg I with the bottom end of the attachment I6 located below or above the bottom of the end of the other ladder leg II a suicientvdistance l,to accommodate the bottom ends of theattachmentgl and leg Il to any ordinary differences in ground surface levels.

A recess I^9 is formed in the face of the adjustable attachment I6, the recessed face being i are simple and inexpensive in themselves and adjacent to the outer face of the ladder leg III.A

A plate 20, which is serrated or formed With teeth to correspond with and engage the teeth or serrated surface of the plate I2, is secured'in the recess I9 by suitable counter-sunk screws. The depth of the recess I9 is made equal to the combined thicknesses of the two plates I2 and 29, when the plates have their teeth in engagement, as shown in Fig. 2, so that the opposed faces of the adjustable attachment I6 and ladder leg ID will contact each other. Suitable washers and clamping nuts 2| are placed on the outer end of the bolts I4 and I5 as shown. l

The manner in which my adjustable ladder can be made to accommodate itself readily to different ground surfaces will be apparent from Figs. 1, 2 and 5. In Fig. 1 the ladder is assumed to be standing on `a level surface. The bottom of the adjustable attachment I6 and the bottom of the leg Il are accordingly arranged so as to be in the same horizontal plane. This of course is the normal position of the adjustable attachment I6. In Fig. 2 the left hand side of the ladder is required to be supported at a lower level than the right hand side. To accommodate the ladder to such uneven ground surface the clamping nuts 2| are loosened and the adjustable attachment is lowered the desired distance, Whereupon the clamping nuts 2| are tightened. This adjustment is very easily and quickly made. In Fig. 5, on the other hand, the right hand side of the ladder is required to be supported Vat a lower level than the left hand side. The same simple, quick adjustment is all that is required to accommodate the ladder to this particular uneven ground surface. In this case the adjustable atvery little work or expense is required with my invention inchanging the ordinary ladder into an adjustable ladder suitable for all practical purposes.

Iclaim:v

An adjustable ladder comprising, a pair of legs connected by rungs, one of said legs extending for a shorter distance below the bottom rung than the other leg, a plate attached to the outside face of said shorter leg, an adjustable vattachment moutned on the outside face of said shorter leg, said attachment being of substantially the same cross section as said shorter leg, a recess in the inside face of said attachment adjacent the outside face of said shorter leg, a second plate secured in said recess, said second plate being longer than said rst mentioned plate and said rst mentioned plate and second plate having cooperating engaging teeth on their opposed faces, the depth of said recess being equal to the combined thicknesses of said plates when said vplates have their teeth inengagement, whereby the opposed faces of said attachment and said shorter leg Wil1 contact each other above and below said recess when the teeth of said plates are in engagement, a pair of clamping bolts extending outwardly through the longitudinal center line of said shorter leg and located above and below said rst mentioned plate, a pair of slots extending along the longitudinal center line of said attachment above and below said recess, said bolts extending through said slots respectively, and clamping nuts on the outer ends of said bolts.

ALEXANDER L. PRUTSMAN. 

